ABSTRACT
The most important characteristic of two-dimensional systems based on triangular geometry is the frustration of the magnetic subsystem. If a Neel antiferromagnetic state is realized on a square lattice under the conditions of antiferromagnetic interaction between the nearest neighbours, then in the case of a triangular lattice this is not so. The magnetic moments in the structure are located in the plane at an angle of 120° with respect to each other. Such an ordered state does not have a gap in the spectrum of magnetic excitations. In the electron spin resonance spectra, a single broadened Dyson line is observed, which indicates that the dispersion plays an important role in absorption. The first-principles calculations in the theory of the density functional showed that the ground quantum state is determined by the family of supersuper exchange interactions between the nearest neighbors, and the spin-configuration model and the wave vector are in good agreement with the experimental neutron scattering data.
